Novel bis-onium salts and the use thereof as photoinitiators

Abstract

Bis-sulfonium, -selenonium, -arsonium, -ammonium, and -phosphonium salts useful as photoinitiators, comprise: an aromatic or heterocyclic aromatic group which absorbs UV or visible radiation and which exhibits a higher energy occupied molecular orbital than at least one other substituent attached to each of the S, Se, As, N or P atoms of said salt; at least one substituent, attached to each of the S, Se, As, N or P atoms of said salt, which comprises an electron-withdrawing group which causes the lowest unoccupied molecular orbital to be localized on the substituent and the S, Se, As, N or P atom of the salt; an insulating group which links said aromatic or heterocyclic aromatic group to each of the S, Se, As, N, or P atoms of said salt, said insulating group essentially preventing π resonance between said aromatic or heterocyclic aromatic group and the other substituents in said salt; and two anions; said salt being capable, upon exposure to UV or visible radiation absorbed by said aromatic or heterocyclic aromatic group, of forming a Bronsted acid. The invention also relates to the use of such photoinitiators.

What is claimed is: 
     
       1. A composition of matter comprising a material curable by a Bronsted acid, and a bis-sulfonium, -selenonium, -arsonium, -ammonium, or -phosphonium salt comprising: an aromatic or heterocyclic aromatic group which absorbs UV or visible radiation and which exhibits a higher energy occupied molecular orbital than at least one substituent attached to each of the S, Se, As, N or P atoms of said salt;   at least one substituent, attached to each of the S, Se, As, N or P atoms of said salt, which comprises an electron-withdrawing group which causes the lowest unoccupied molecular orbital to be localized on the substituent and the S, Se, As, N or P atom of the salt;   an insulating group which links said aromatic or heterocyclic aromatic group to each of the S, Se, As, N, or P atoms of said salt, said insulating group essentially preventing x resonance between said aromatic or heterocyclic aromatic group and the other substituents in said salt; and   two anions; said salt being capable, upon exposure to UV or visible radiation absorbed by said aromatic or heterocyclic aromatic group, of forming a Bronsted acid.     
     
     
       2. A composition of matter comprising a material curable by a Bronsted acid, and a compound which has one of the following formulas: ##STR14## wherein: R 1  represents an electron donating aromatic or heterocyclic aromatic group which absorbs UV or visible radiation and which exhibits a higher energy occupied molecular orbital greater than R 3  and R 6  ; R 2  and R 5  each, independently, represent the same substituent as R 3  or R 6  or an alkyl group having from 1 to 18 carbon atoms;   L 1  and L 2  each, independently, represent a linking group which essentially prevents π resonance between R 1  and the remainder of the compound;   R 3  and R 6  each, independently, represent an electron withdrawing alkyl, aryl or heterocyclic group, which electron withdrawing group causes the lowest unoccupied molecular orbital to be localized on R 3 , R 6  and the S, Se, As, N or P atoms of the salt;   J 1  and J 2  each, independently, represent an S, Se, As, N or P atom, and,   when J 1  or J 2  represents As, N or P, R 4  and R 7 , respectively, represent the same substituent as R 3 , R 4 , R 5  or R 6  and, when J 1  or J 2  represents an S or Se atom, R 4  and R 7  each, independently, represent O or an electron pair; and,   W 1   -  and W 2   -  each, independently, represents an anion capable of forming a Bronsted acid having a pKa of less than 7,   said compound being capable, upon exposure to UV or visible radiation absorbed by R 1 , of forming a Bronsted acid.   
     
     
       3. A composition of matter as defined in claim 2 in which, in the definition of the substituents in the formulas, L 1  and L 2  each represents a phenyl or a naphthyl linkage and J 1  and J 2  are attached to the phenyl or naphthyl linkage in the 3-position with respect to R 1 . 
     
     
       4. A composition of matter comprising a material curable by a Bronsted acid, and a bis-sulfonium, -selenonium, -arsonium, -ammonium, or -phosphonium salt comprising: an aromatic or heterocyclic aromatic group which absorbs UV or visible radiation and which exhibits a higher energy occupied molecular orbital than at least one substituent attached to each of the S, Se, As, N or P atoms of said salt;   at least one substituent, attached to each of the S, Se, As, N or P atoms of said salt, which comprises an electron-withdrawing group which causes the lowest unoccupied molecular orbital to be localized on the substituent and the S, Se, As, N or P atom of the salt;   an insulating group which links said aromatic or heterocyclic aromatic group to each of the S, Se, As, N, or P atoms of said salt, said insulating group essentially preventing π resonance between said aromatic or heterocyclic aromatic group and the other substituents in said salt; and   two anions; said salt being capable, upon exposure to UV or visible radiation absorbed by said aromatic or heterocyclic aromatic group, of forming a Bronsted acid.     
     
     
       5. A polyester support having thereon a coating comprising a material curable by a Bronsted acid and a compound having one of the following formulas: ##STR15## wherein: R 1  represents an electron donating aromatic or heterocyclic aromatic group which absorbs UV or visible radiation and which exhibits a higher energy occupied molecular orbital greater than R 3  and R 6  ; R 2  and R 5  each, independently, represent the same substituent as R 3  or R 6  or an alkyl group having from 1 to 18 carbon atoms;   L 1  and L 2  each, independently, represent a linking group which essentially prevents π resonance between R 1  and the remainder of the compound;   R 3  and R 6  each, independently, represent an electron withdrawing alkyl, aryl or heterocyclic group, which electron withdrawing group causes the lowest unoccupied molecular orbital to be localized on R 3 , R 6  and the S, Se, As, N or P atom of the salt;   J 1  and J 2  each, independently, represent an S, Se, As, N or P atom, and,   when J 1  or J 2  represents As, N or P, R 4  and R 7 , respectively, represent the same substituent as R 3 , R 4 , R 5  or R 6  and, when J 1  or J 2  represents an S or Se atom, R 4  and R 7  each, independently, represent O or an electron pair; and,   W 1   -  and W 2   -  each, independently, represents an anion capable of forming a Bronsted acid having a pKa of less than 7,   said compound being capable, upon exposure to UV or visible radiation absorbed by R 1 , of forming a Bronsted acid.